Critical Review of Coupled Flux Formulations for Clay Membranes Based on Nonequilibrium Thermodynamics

Extensive research conducted over the past several decades has indicated that semipermeable membrane behavior (i.e., the ability of a porous medium to restrict the passage of solutes) may have a significant influence on solute migration through a wide variety of clay-rich soils, including both natural clay formations (aquitards, aquicludes) and engineered clay barriers (e.g., landfill liners and vertical cutoff walls). Restricted solute migration through clay membranes generally has been described using coupled flux formulations based on nonequilibrium (irreversible) thermodynamics. However, these formulations have differed depending on the assumptions inherent in the theoretical development, resulting in some confusion regarding the applicability of the formulations. Accordingly, a critical review of coupled flux formulations for liquid, current, and solutes through a semipermeable clay membrane under isothermal conditions is undertaken with the goals of explicitly resolving differences among the formulations and illustrating the significance of the differences from theoretical and practical perspectives. Formulations based on single-solute systems (i.e., uncharged solute), single-salt systems, and general systems containing multiple cations or anions are presented. Also, expressions relating the phenomenological coefficients in the coupled flux equations to relevant soil properties (e.g., hydraulic conductivity and effective diffusion coefficient) are summarized for each system. A major difference in the formulations is shown to exist depending on whether counter diffusion or salt diffusion is assumed. This difference between counter and salt diffusion is shown to affect the interpretation of values for the effective diffusion coefficient in a clay membrane based on previously published experimental data. Solute transport theories based on both counter and salt diffusion then are used to re-evaluate previously published column test data for the same clay membrane. The results indicate that, despite the theoretical inconsistency between the counter-diffusion assumption and the salt-diffusion conditions of the experiments, the predictive ability of solute transport theory based on the assumption of counter diffusion is not significantly different from that based on the assumption of salt diffusion, provided that the input parameters used in each theory are derived under the same assumption inherent in the theory. Nonetheless, salt-diffusion theory is fundamentally correct and, therefore, is more appropriate for problems involving salt diffusion in clay membranes. Finally, the fact that solute diffusion cannot occur in an ideal or perfect membrane is not explicitly captured in any of the theoretical expressions for total solute flux in clay membranes, but rather is generally accounted for via inclusion of an effective porosity, ne, or a restrictive tortuosity factor, tr, in the formulation of Fick\u27s first law for diffusion. Both ne and tr have been correlated as a linear function of membrane efficiency. This linear correlation is supported theoretically by pore-scale modeling of solid-liquid interactions, but experimental support is limited. Additional data are needed to bolster the validity of the linear correlation for clay membranes

Unused Medications and Disposal Patterns at Home: Findings from a Medicare Patient Survey and Claims Data

Objective: To examine what medications are most frequently left unused by patients, how much is left unused, and how these medications are disposed of among Medicare beneficiaries. Design: Secondary data analysis combining insurance claims and telephone survey data of Medicare Advantage members. Setting: Regional health plan in Central Pennsylvania. Participants: Seven hundred twenty-one Medicare Advantage members who had Part D coverage through the plan as of December 31, 2013, and completed the telephone survey in May 2014. Intervention: Telephone survey conducted by a survey research center. Main outcome measure: Member survey response. Results: Of the 2,994 medications in the dataset, 247 (8%) were reported being left unused by patients. Of the 247, the most common medications were those for pain (15%), hypertension (14%), antibiotics (11%), and psychiatric disorders (9%). Approximately 15% of unused medications were controlled substances. The reasons for being unused varied by drug type. For example, for pain medications, adverse effects and overprescribing were the most commonly cited reasons; for hypertension medications, “dosage changed by doctor” was the most common reason. Most commonly, unused portions accounted for approximately 25% to 50% of the unused medications identified by patients. Approximately 11% of unused medication was disposed of via drug take-back programs, whereas the majority was kept in a cabinet (55%), thrown in the trash (14%), or flushed down the toilet (9%). Conclusion: A lack of patient adherence alone does not explain unused medications and their improper disposal. Community-level interventions designed to improve prescription efficiency and patient awareness of appropriate disposal methodsdparticularly of controlled substancesdare necessary to reduce the potentially harmful effects of improper disposal of unused medications

High-speed spectral nanocytology for early cancer screening

High-throughput partial wave spectroscopy (HTPWS) is introduced as a high-speed spectral nanocytology technique that utilizes the field effect of carcinogenesis to perform minimally invasive cancer screening on at-risk populations. HTPWS uses fully automated hardware and an acousto-optic tunable filter to scan slides at low magnification, to select cells, and to rapidly acquire spectra at each spatial pixel in a cell between 450 and 700 nm, completing measurements of 30 cells in 40 min. Statistical quantitative analysis on the size and density of intracellular nanostructures extracted from the spectra at each pixel in a cell yields the diagnostic biomarker, disorder strength (Ld). Linear correlation between Ld and the length scale of nanostructures was measured in phantoms with R2=0.93. Diagnostic sensitivity was demonstrated by measuring significantly higher Ld from a human colon cancer cell line (HT29 control vector) than a less aggressive variant (epidermal growth factor receptor knockdown). Clinical diagnostic performance for lung cancer screening was tested on 23 patients, yielding a significant difference in Ld between smokers and cancer patients, p=0.02 and effect size=1.00. The high-throughput performance, nanoscale sensitivity, and diagnostic sensitivity make HTPWS a potentially clinically relevant modality for risk stratification of the large populations at risk of developing cancer

Nanocytological field carcinogenesis detection to mitigate overdiagnosis of prostate cancer: a proof of concept study.

To determine whether nano-architectural interrogation of prostate field carcinogenesis can be used to predict prognosis in patients with early stage (Gleason 6) prostate cancer (PCa), which is mostly indolent but frequently unnecessarily treated.We previously developed partial wave spectroscopic microscopy (PWS) that enables quantification of the nanoscale intracellular architecture (20-200 nm length scale) with remarkable accuracy. We adapted this technique to assess prostate needle core biopsies in a case control study from men with Gleason 6 disease who either progressed (n = 20) or remained indolent (n = 18) over a ~3 year follow up. We measured the parameter disorder strength (Ld) characterizing the spatial heterogeneity of the nanoscale cellular structure and nuclear morphology from the microscopically normal mucosa ~150 histologically normal epithelial cells.There was a profound increase in nano-architectural disorder between progressors and non-progressors. Indeed, the Ld from future progressors was dramatically increased when compared to future non-progressors (1±0.065 versus 1.30±0.0614, respectively p = 0.002). The area under the receiver operator characteristic curve (AUC) was 0.79, yielding a sensitivity of 88% and specificity of 72% for discriminating between progressors and non-progressors. This was not confounded by demographic factors (age, smoking status, race, obesity), thus supporting the robustness of the approach.We demonstrate, for the first time, that nano-architectural alterations occur in prostate cancer field carcinogenesis and can be exploited to predict prognosis of early stage PCa. This approach has promise in addressing the clinically vexing dilemma of management of Gleason 6 PCa and may provide a paradigm for dealing with the larger issue of cancer overdiagnosis

Phase 2 Study of the Safety and Antitumor Activity of Apalutamide (ARN-509), a Potent Androgen Receptor Antagonist, in the High-risk Nonmetastatic Castration-resistant Prostate Cancer Cohort

Background: Apalutamide is a potent androgen receptor (AR) antagonist that targets the AR ligand-binding domain and prevents AR nuclear translocation, DNA binding, and transcription of AR gene targets. Objective: To evaluate the activity and safety of apalutamide in patients with high-risk nonmetastatic castration-resistant prostate cancer (nmCRPC). Design, setting, and participants We conducted a multicenter phase 2 study of nmCRPC patients with a high risk for progression (prostate-specific antigen [PSA] ≥8 ng/ml or PSA doubling time [PSA DT] ≤10 mo). Intervention Patients received 240 mg/d apalutamide while continuing on androgen-deprivation therapy. Outcome measurements and statistical analysis Primary end point was 12-wk PSA response (Prostate Cancer Working Group 2 criteria). Secondary end points included safety, time to PSA progression (TTPP), and metastasis-free survival (MFS). Results and limitations A total of 51 patients were enrolled; four patients with metastatic disease were excluded from the efficacy analysis. Patient characteristics included median age, 71 yr; Eastern Cooperative Oncology Group performance status 0 (76%); Gleason score ≤ 7 (57%); median PSA 10.7 ng/ml; and PSA DT ≤10 mo (45%). At median follow-up of 28.0 mo, 18 patients (35%) remained in the study. Overall, 89% of patients had ≥50% PSA decline at 12 wk. Median TTPP was 24.0 mo (95% confidence interval [CI], 16.3 mo–not reached [NR]); median MFS was NR (95% CI, 33.4 mo–NR). Most of the patients discontinued study treatment (n = 33) due to disease progression (n = 11 [22%]) or adverse events (AEs) (n = 9 [18%]). The most common AE was fatigue (any grade, n = 31 [61%]) although grade ≥3 fatigue was uncommon (n = 2 [4%]). These represent the first apalutamide nmCRPC patient clinical data. Conclusions: In high-risk nmCRPC patients, apalutamide was safe with robust activity based on durable PSA responses and disease control. Patient summary Antitumor activity and the safety of apalutamide in patients with nonmetastatic castration-resistant prostate cancer support continued development in this setting. Trial registration ClinicalTrials.gov identifier NCT0117189

(a) Mean disorder strength (Ld) in non-progressors (n = 18) and progressors (n = 20) show a statistically significant difference between the two patient groups (p = 0.002) with an effect size of diagnosis = 110%.

<p>The median follow up time was 34.2 months.</p

The ROC curve obtained from the composite dataset (n = 38) demonstrates an area under curve (AUC) of 0.80.

<p>This translated into a sensitivity = 88% and specificity = 72% for discriminating between progressors and non-progressors.</p